1. Technical Field of the Invention
The present invention relates generally to a gas sensor which may be employed in an air-fuel ratio control system for automotive vehicles for measuring the concentration of gas such as O2, NOx, or CO, and more particularly to an improved compact structure of such a gas sensor and a production method thereof.
2. Background Art
It is known that control of burning of an internal combustion engines as a function of the concentration of oxygen contained in exhaust gasses and the air-fuel ratio of a mixture is effective in the energy saving and the emission control. As one of gas sensors suitable for measuring the concentration of oxygen in exhaust gasses, a gas sensor including a solid electrolyte body made of zirconia is known. This type of gas sensor is, however, required to be reduced in size and production costs and improved in durability and reliability. The approach to satisfaction of these requirements has still left room for improvement.